1. Pteridium aquilinum (Linnaeus) Kuhn var. latiusculum (Desvaux) Underwood ex A. Heller, Cat. N. Amer. Pl., ed. 3. 17. 1909.
Pteris latiuscula Desvaux, Mém. Soc. Linn. Paris 6(3): 303. 1827; Pteridium aquilinum f. glabrum Tardieu & C. Christensen; P. aquilinum subsp. japonicum (Nakai) Á. Löve & D. Löve; P. aquilinum var. japonicum Nakai; P. aquilinum subsp. latiusculum (Desvaux) Hultén; P. japonicum Tardieu & C. Christensen; P. latiusculum (Desvaux) Hieronymus ex Fries; Pteris lanuginosa Sprengel (1821), not Bory ex Willdenow (1810).
Plants up to 2 m tall. Rhizome long creeping, densely castaneous hairy. Fronds erect, 0.5-1.5 m (sometimes larger in shaded forms); stipe brown, up to 40 cm, woody, basally with short brown hairs, apically glabrous; lamina 3- or 4-pinnate-pinnatifid, triangular to oblong-ovate in outline when pressed, leathery; basal pinnae as long as to ca. 1/2 length of lamina; rachis pale brown, thinly pubescent, becoming glabrous; lobes present between 2 adjacent segments; pinnae ascending or horizontal, ovate-triangular to oblong, up to 40 × 15 cm, apex acute; pinnules or segments linear to oblong, glabrous except for pinnule margins and midvein, deeply pinnatifid in larger pinnae, apex shortly bluntly or long caudate. Sori elongate, submarginal on ultimate segments; outer indusium ca. 0.5 mm wide, membranous, ciliate, inner indusium vestigial and fimbriate. 2n = 104.
Sunny slopes and forest margins; 100-800 m. Throughout China, but mostly in S China including Taiwan [Japan (including Ryukyu Islands); Europe, North America].
The typical variety is distributed in Africa and Europe.